Abstract: In this paper, an on-line monitoring method of high temperature pipeline wall thickness based on the shear horizontal(SH) guided wave was developed. It uses a strip waveguide as thermal buffer structure to quickly insulate the piezoelectric transducer from high temperature pipelines, and at the same time, a non-dispersive SH guided wave is delivered through the waveguide for measuring wall thickness. A method of excitation and reception of non-dispersive shear horizontal guided wave in strip waveguides was proposed, and a dry coupling clamping device between waveguides and high temperature pipeline was designed. Finally, the feasibility of SH ultrasonic guided wave method for on-line monitoring of high temperature (600℃) pipeline wall thickness was verified by experiments.